The invention relates to a record carrier on which a main data file and a control file have been recorded, the control data in the control file being intended for controlling the reproduction of representations of main data in the main data file during or after read-out of the main data file, the main data file and the control data file being derived from a main data signal and a control data signal respectively in conformity with the same predetermined formatting and encoding rules.
The invention further relates to a method of recording a main data file and a control file on a record carrier, in which prior to recording the main data file is derived from a main data signal in accordance with predetermined formatting and coding rules and in which the control file is derived from a control data signal in accordance with the same formatting and coding rules.
The invention further relates to a device for recording files on a record carrier, the device comprising means for deriving from a main data signal and a control data signal, a main data file to be recorded and a control data file to be recorded respectively in accordance with predetermined formatting and encoding rules which are identical for both files.
The invention further relates to a device for reading said record carrier, which device comprises means for reading the recorded files, decoding and deformatting means for recovering in conformity with predetermined decoding and deformatting rules the main data signal and the control data signal from the files thus read, a signal processing unit coupled to the decoding and deformatting means to process the main data signal, and a control unit coupled to the decoding and deformatting means to receive the control signal.
Such a record carrier and method and such devices are known, inter alia from the book "Compact Disc Interactive, a designer overview", edited by Philips International and published by Kluwer (ISBN 9090121219).
This book describes the so-called CDI system, which enables main data files, for example picture files, to be recorded on a Compact Disc, a picture data signal being formatted and encoded in accordance with the CD-I standard prior to recording. Control files, in the form of application programs, are also recorded. Prior to recording the control data signal is converted into the control file in accordance with the same formatting and encoding rules as applied in the conversion of the picture information signal into the main data file. The picture data file thus recorded can be read and representations of the information in the picture data file can be reproduced by means of a so-called CD-I player. The application program is then read first. This application program contains the control information necessary for controlling the reproduction of the representations.
The picture data file is read at a high bit rate, which has the advantage of a short read-out time for the picture data file. However, the high bit rate during reading also means that the control file becomes available at the same high bit rate. Since it is customary that a CD-I player comprises a computer system for processing both the main data file and the control file this does not pose a problem.
The use of such a computer system has the advantage that the CD-I player can be used for a variety of purposes. However, a drawback is that such a computer system is rather expensive. If the CD-I system is used exclusively for storing on a record carrier specific information, such as for example picture information originating from photographic negatives or slides, it may be desirable to have a dedicated read device, which is capable only of reading record carriers on which said specific information has been recorded. For processing the information from the main data file it is then preferred to use a dedicated and hence cheaper data processing unit rather than a computer system.
However, a problem which is then encountered is that a control unit must be used which is capable of reading in the control data from the control file, which is presented at a high bit rate. However, the control functions to be performed by said control unit do not require the use of a control unit with a high signal-processing speed, which means that a control unit with a high signal-processing speed, which is expensive, has to be used merely for reading in the control data.